Abstract

Biomass fuelled trigeneration is the term given to the system which is the on-site generation of electricity, heat and cooling simultaneously, using biomass as the fuel source. As a form of the renewable energy sources biomass is not intermittent, location-dependent or very difficult to store. If grown sustainably, biomass can be considered to be CO2 neutral. Biomass, therefore, would be a promising option for the future to contribute both to the reduction of greenhouse gases and to the solution of replacing fossil fuels in power plants. For a wide range of commercial buildings, biomass trigeneration offers aneconomical solution of providing power, heat and cooling which is more environmentally friendly than conventional methods.This work focuses on the modelling, simulation and techno-economic analysis of small scale biomass trigeneration applications. The Organic Rankine Cycle (ORC) integrated with conventional combustion provides electricity for building use. The waste heat recovered from the ORC system and exhaust gases is used to supply hot water to space heating and excess heat is also used to drive an absorption cooling system. In order to use energy resources most efficiently, the proposed process is modelled and simulated using the ECLIPSE process simulation package. Based on the results achieved, the key technical and environmental issues have been examined. The study also investigates the impact of different biomass feedstock on the performance of trigeneration plant, biomass ash content ranges from 0.57 to 14.26% ash and a range of moisture content 10.6e33.51%. The calorific value across the biomass sources ranges between 16.56 and 17.97 MJ/kg daf. Finally, an economic evaluation of the system is performed alongwith sensitivity analyses such as capital investments, plant load factors and fuel costs. The results show that the maximum efficiencies and the best breakeven electricity selling price for the cases considered in this study are as follows: 11.1% and 221 £/MWh for power only, 85.0% and 87 £/MWh for combined heat and power and 71.7% and 103 £/kWh for trigeneration respectively.